$4000 to spend on a SS power amp - help me choose

Spectron Musician III
Parasound JC-1 Halo Monoblocks
Mccormack DNA 2

In your case, I would definitely go for active bi-amping and keep the Graaf for the mid-hi. In that case, you'll need an SS that typically has a hefty PS and is stable into low loads -- but you certainly don't need a new, giga$ powerhouse, that's over-engineered to provide an extension from DC to daylight AND the best mids, highs etc:). Especially if you're crossing over at or below 200Hz.
So any 100+W/channel, (used) Krell, (used Lev), Bryston, Nad, Adcom, etc should do. Don't vmps offer an amp of their own, too???

For the low end>>> An Eagle 4 or 7. As 'Hammer" used to say "You can't touch that". I have a 4 and I'll bet it can out-bass the list for 1k.

I went from tubes to Rowland gear and have not gone back. Jallen

You may add Sunfire 600-II.